This invention relates generally to an improved lock assembly for use in secure locking of a sliding door such as a sliding glass patio door or the like. More particularly, this invention relates to an improved high security lock assembly designed to safely and positively lock a patio door or the like against unauthorized entry.
Sliding doors such as sliding glass patio doors and the like are will known in the art and are commonly used in residential dwellings, apartment units and the like. Such sliding glass patio doors typically comprise one or more enlarged glass panes carried in a surrounding metal or wooden frame adapted for sliding movement back and forth upon a lower track or rail. A vertical stile along one edge of the sliding door normally carries a lock assembly adapted for keyless operation from the indoor side of the door, and, if desired, for keyed operation from the outdoor side of the door. This lock assembly typically operates a hook-shaped latch member for selective engagement with a matingly shaped latch keeper mounted on the adjacent door jamb for locking the door against entry.
It is well recognized, however, that sliding glass patio doors of the above-described type are frequently opened relatively easily by unauthorized intruders. More particularly, such sliding glass doors normally ride upon their associated track or rail with sufficient freedom of motion to permit an unauthorized intruder to lift or otherwise shift the door from the track or rail even when the door is locked. Accordingly, it is possible for an intruder to lift or shift the locked door sufficiently from the outdoor side to disengage the latch member from the latch keeper to permit the door to be opened, or, in some instances, to permit the door to be removed entirely from the track or rail.
The prior art includes a wide variety of proposed mechanisms intended to prevent unauthorized opening of an otherwise locked sliding glass patio door. Such mechanisms include, for example, many different types of secondary lock pins and the like which are normally attached to the door as removable items, wherein these secondary lock pins are intended to cooperate with the standard door latch member to improve security in the locked condition by preventing lifting or shifting, etc., of the door from the outdoor side. However, the use of a secondary lock pin on a sliding glass door is relatively inconvenient since such devices must be set in the locked condition separately from the standard latch member, whereby actual locking of the secondary lock pin in often forgotten or disregarded. Moreover, removable secondary lock pins devices are necessarily separated from the door in the unlocked condition and are thus subject to becoming easily lost. Other secondary lock pin devices requiring permanent installation onto the sliding door are not widely used in view of the tools and skills required to achieve a proper permanent installation.
There exists, therefore, a significant need for improvements in locking devices for sliding doors such as sliding glass patio doors and the like. The present invention fulfills these needs and provides further related advantages.